Organometallic MFU-4l(arge) Metal–Organic Frameworks

Abstract

Ligand exchange reactions at the Kuratowski-type secondary building unit in MFU-4l(arge) metal–organic frameworks (MOFs) result in organometallic porous compounds with metal–carbon bonds of the general formula [Zn5L x Cl4–x (BTDD)3] (4 ≥ x > 3; L = methanido, ethanido, n-butanido, tert-butanido, 3,3-dimethyl-1-butyn-1-ido; H2-BTDD = bis­(1H-1,2,3-triazolo­[4,5-b]­[4′,5′-i])­dibenzo­[1,4]­dioxin) and [Zn1.5Co3.5Me3.1Cl0.9(BTDD)3]. The compounds were characterized by FT-IR, EDX spectroscopy, X-ray powder diffraction (XRPD), and argon adsorption measurements. VT-XRPD, TGA, and TG-MS measurements were applied to investigate the thermal and oxidative stability of the organometallic Zn-MFU-4l derivatives. The hydrolytic stability of all compounds was examined, and a conversion of the methanide to hydroxide ligands is observed in the cobalt-containing compound. DRIFTS measurements of the resulting framework with the composition [Zn1.4Co3.6(OH)3.1Cl0.9(BTDD)3] revealed a mechanism of carbon dioxide binding similar to that of carbonic anhydrase.

Supercooled water confined in a metal-organic framework

“…MFU-4l-HCOO (where MFU stands for "Metal-Organic Framework Ulm-University") is derived from MFU-4l. 63,64 As noted in Ref. 65 ), which is linked to six N-donor atoms of six different ligands, and by four peripheral tetrahedrally coordinated zinc ions (Zn t ).…”

“…MFU-4l-HCOO (where MFU stands for "Metal-Organic Framework Ulm-University") is derived from MFU-4l. 63,64 As noted in Ref. 65, the latter is composed of Zn(II) ions and bis(1H-1,2,3-triazolo [4,5-b], [4',5'-i])dibenzo [1,4]dioxin (H 2 -BTDD) as a ligand.…”

Insights into CO2 Adsorption in M–OH Functionalized MOFs

“…The asymmetric stretch at 1633 cm −1 closely resembles those reported upon CO 2 adsorption in MFU-4l-ZnOH (1660 cm −1 ) and MFU-4l-CoOH (1636 cm −1 ). 35,36 In contrast, 3b-CO 2 gives rise to a strongly red-shifted asymmetric v(CO 2 ) band at 1585 cm −1 and a v(O−H•••O) band at 2657 cm −1 that have been attributed to the presence of strong intercluster hydrogen-bonding interactions. Given that the IR bands observed for 1a-CO 2 more closely match those of the MFU-4l analogues, CO 2 adsorption does not appear to be accompanied by formation of well-defined intercluster hydrogen-bonding interactions.…”

“…In this regard, MOFs containing nucleophilic amines appended to organic linkers or grafted at metal nodes have shown excellent performance for trace CO 2 capture via chemisorptive processes akin to liquid amine scrubbing. − The benzotriazolate MOFs MFU-4 ( 1 ), MFU-4 l ( 2 ), and CFA-1 ( 3 ) have received considerable attention for applications in gas adsorption and catalysis owing to their Kuratowski-type secondary building units (SBUs) which contain divalent transition metal ions with terminal X-type ligands and are highly amenable to postsynthetic cation exchange (Figure ). − Recently, we and others have developed methods to generate nucleophilic transition metal hydroxide (M–OH) groups at the SBUs of benzotriazolate MOFs and investigated their reactivity toward CO 2 . − These M–OH groups resemble the active sites of α-carbonic anhydrases, and this resemblance has proven to be both structural and functional as these materials tend to adsorb CO 2 at low pressures via a metal hydroxide/bicarbonate chemisorptive mechanism.…”

Benign Synthesis and Modification of a Zn–Azolate Metal–Organic Framework for Enhanced Ammonia Uptake and Catalytic Hydrolysis of an Organophosphorus Chemical

“…Moreover, consistent N 2 adsorption/desorption isotherms (77 K) of MFU-4l and MFU-4l-(OH) confirmed the well-maintained porosity of MFU-4l-(OH) (Figure S8). According to diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies in Figure 3b, a peak at ∼3696 cm −1 (belonging to the O−H stretching peak), 41 appeared after the base treatment, signifying the formation of Zn(II)−OH. X-ray photoelectron spectroscopy (XPS) probed the presence of −Cl present in MFU-4l before and after the exchange treatment.…”